Abstract
In the production and gathering process of coal gas, the complex composition of the coal gas, harsh environments, the complex medium, and high content of solid particles in slurry cause the equipment malfunctions and even failure because of erosion and corrosion. In the present study, COMSOL multi-physics finite element simulation software is used to simulate the erosion–corrosion behaviors of elbow in key chemical equipments. The electrochemical corrosion, solid particle erosion, chemical reaction, and turbulent flow are coupled together. The particle count method is proposed to clarify the erosion phenomenon. The simulation results show that particles with high turbulent intensity hit the wall of elbow directly, which forms a slanted elliptical erosion zone on the extrados surface at 40°–50°. The chemical reaction in turbulence has a difference in the concentration distribution of substances, and this phenomenon leads to different magnitudes of the corrosion current densities in the tube. Moreover, 1/6 released particles hit the extrados surface of the elbow. These findings are beneficial to understand the erosion–corrosion phenomena and design the elbow in key chemical equipment.
Highlights
Erosion-corrosion is a comprehensive type of the failure process including the mechanical and electrochemical action [1]
CO2 is dissolved in water forming the saturated carbonic acid solution that results in the electrochemical corrosion of the pipeline under the operational service or out of service conditions
Because of a strong demand for the analysis of erosion–corrosion problems, this study focuses on the following aspects: numerical study on the fluid flow, erosion, and corrosion along the axial direction of the pipeline for the real field cases and the related phenomenon of erosion–corrosion expecting to provide detailed and reasonable analysis of the failure incurred by the erosion–corrosion
Summary
Erosion-corrosion is a comprehensive type of the failure process including the mechanical and electrochemical action [1]. Researchers performed only CFD simulation analysis, and the velocity vector of the flow filed is used to characterize the serious position of erosion [3] In these researches, there were no comprehensive simulated erosion failure processes, such as electrochemical corrosion through current density or mass loss per unit area. A large amount of information can be obtained, including electrochemical reactions, potentials in electrolytes and metal structures, homogeneous chemical reactions, and unique phenomena in the corrosion process The output of such an analysis is the localized current density, which is used to calculate the average corrosion rate of any component over a given period of time. It is expected to obtain the turbulence characteristics, substance concentration distribution, electrochemical corrosion current density, the quantities of particles striking the wall and mass loss per unit area. The stress, temperature, and corrosion cracks of the key parts of the pipeline between corrosion development and status are achieved, and the corrosion leakage prediction model is established and the corrosion development trend and prediction method of leakage occurrence location is predicted
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